Backing up HP28s user data via IR port

[voltaage]

Hello and Happy New 2023.

I finally upgraded myself from a long friend of mine, my HP 28S, with the mighty 50g. I've been using the little clamshell and it's been a blast. I love the environment, the keys, the display... the whole experience of using it.

But, as far as temptation goes, the desire of exploring the huge xxxRPL library written for the 48 series and up, with the consquent frustration of keying in all the code just to painstaikingly check of errors (seriously, it was far easier with numeric codes) pushed me to get this one. Plus, it's been a long time since I wanted this (1 decade +) but never bother because of some fear it would be awkward to have the alpha keyboard and the functions in all one space.

So as you might have read the title, I want to backup some data that I have on the I/O limited 28S. I've read this thread where it mentions how to build an IR Arduino device to capture the printer output. But that in just a glance requires the use of a special HP transceiver module that is no longer sold (and it's not cheap to buy).

One of the options that I'm thinking of is listing the program on the redeye, scanning, OCR'ing it and upload into the 50g. But that imply some editing to make sure it's been been transferred properly. Especially special RPL symbols in programs. Probably it works I need to see.

Is there a more automatic way of doing this job? Like when you dump image roms in the 50g?

Bear in mind that I'm new to the use of the 50g, so I beg your pardon if the answer is too obvious but my inexperience is blindfolding me.

[robjordan]

Hi

By coincidence I've also been going down this path, in my case to back up equations from the HP-17bII. I read Martin Hepperle's documents that you referenced, and I was lucky enough to get one of the C4103a HP IR receivers for £5 from ebay. In fact, oddly enough there were two relatively cheap ones on ebay in the UK the same day. So I would suggest to keep tracking ebay in case you find a cheap one.

There are other ways... this fellow on Hackaday was successful in building an IR interface to a 28S using Vishay TSOP4133 IR receiver, even though there are real difficulties in receiving the HP IR protocol using this type of integrating IR receiver.

So I have built a device similar to Martin's. I used a different processor (an ATTiny), and wrote my own software inspired by Martin's approach (because - you know - fun!). I connect my device to a USB port and run a serial terminal on my PC (I run Linux), and when I print an equation on the calculator, the characters appear on the serial terminal, and I can cut and paste them into a document to save the equation in case the calculator loses its memory.

I guess in your case, you could use the text you cut from the serial terminal to import into the HP50G.

My code is here, and I'm attaching a couple of photos. It needs some tweaks to support 28S (I have one, so I may progress with this shortly).

Cheers
Rob

[rprosperi]

(01-09-2023 02:26 AM)voltaage Wrote:  So as you might have read the title, I want to backup some data that I have on the I/O limited 28S. I've read this thread where it mentions how to build an IR Arduino device to capture the printer output. But that in just a glance requires the use of a special HP transceiver module that is no longer sold (and it's not cheap to buy).

These units are readily available on eBay, starting at $14 w/shipping included (though possibly more in Germany?). Seems pretty cheap to me... These have been used by numerous members here and have been found to reliable and consistent (which not all old IR devices can clam). Just an FYI.

[EugeneNine]

Doesn't the 28 transfer via kermit like the 48?
Even so when you print from the 48 its characters so capturing a print you wouldn't need to OCR.

[C.Ret]

(01-09-2023 02:26 AM)voltaage Wrote:  Is there a more automatic way of doing this job?

Hello,

Why not just use an IR printer to print all your programs and data in your directories and subdirectories?

The VARS command (from MEMORY menu) used in conjunction with PRVAR (from PRINT menu) produces clear, detailed, and labeled printouts of the contents of any user's directory.

[Jake Schwartz]

(01-09-2023 05:35 PM)EugeneNine Wrote:  Doesn't the 28 transfer via kermit like the 48?
Even so when you print from the 48 its characters so capturing a print you wouldn't need to OCR.

The 28 has no I/O ports.
Jake

[EugeneNine]

(01-09-2023 10:14 PM)Jake Schwartz Wrote:  

(01-09-2023 05:35 PM)EugeneNine Wrote:  Doesn't the 28 transfer via kermit like the 48?
Even so when you print from the 48 its characters so capturing a print you wouldn't need to OCR.

The 28 has no I/O ports.
Jake

via IR.
The 48 will speak kermit wired or IR

[DavidM]

(01-09-2023 11:57 PM)EugeneNine Wrote:  The 48 will speak kermit wired or IR

I don't believe the 28 has bi-directional IR capability, and likewise doesn't have any documented support for communications (other than some printing commands, of course).

It may be possible to run the INPRT command on a 48sx or 48gx to receive the results of a print command issued on the 28. I don't believe there's a version of INPRT for the 49/50 platforms, though.

Does anyone have both a 28S and a 48sx/gx that they could try this on? The description for INPRT includes this comment:

Quote:"For the HP 28, HP 18C, and HP 19B: Just line up the calculator's LED between the E and T of HEWLETT on the HP 48's Hewlett-Packard logo."

So it appears that it may work to at least get your programs in text form.

[FLISZT]

As DavidM said, the hp-28 does not have bi-directional IR capability and, furthermore, the infrared signals of the hp-28 are different from those used by the hp-50.
So, unfortunately, my hp-28s can't send data to one of my hp-50g.

Two hp-50 can "exchange" (not full-duplex!) data via the IF port or via a specific and (I think) very rare wire, if one owns one.

It must be possible for two hp-48 as well, at least of the same serie: S/SX ↔ S/SX or G/GX ↔ G/GX.
But S/SX ↔ G/GX… does it work?

There was a thread in the forum years ago, if I remember correctly, that talked about all this (IF and hp-28-48-etc)... but I didn't find it!

[EugeneNine]

so its been a few years but I would send IR from my 48sx to various pc's over serial. The trick is most bought IR adapters have a small mcu in them which 'speaks' IRDA and the HP's don't. You have to build your own by just connecting an IR tx/rx pair to the serial port. Its been many years but I'd use one of the IR pair sets Radio Shack sold and a rs232 level shifter like the max232.
Now a days I'm using a USB-rs232 but going from usb 5v to +/-12v for rs232 and then back to 5v for the ir pair is overkill, it would be easier to use one of the USB-serial @5v or 3.3v like what are used for programming small mcu' like Arduino and such. I should still have some parts lying around to test with.

[FLISZT]

According to this thread in the Old HP Forum, a device, that allowed data transmission (via infrared) from a hp-28 to a PC, did exist.

I wish I had known that at the time!

[FLISZT]

You may also want to take a look at:

https://www.hpmuseum.org/cgi-sys/cgiwrap...ead=194140

https://www.hpcalc.org/details/3540